A continuing problem in the development of optical fibre cables is that of providing a high fibre count in a small cable volume in an effort to reduce costs. In a conventional cable construction a number of fibres are disposed around a central strength member or king wire which provides strain relief for the fibres. In such an arrangement the number of fibres that can be accommodated is restricted by the limited space around the king wire. In an attempt to overcome this problem various workers have investigated structures incorporating ribbon fibre elements. Such structures generally comprise a core member having a number of longitudinal slots each of which contains one or more fibre ribbons. Although these cable structures can provide a high fibre count, the cable is relatively bulky and is thus unsuitable, e.g. for aerial or for submarine applications where the weight and volume of the cable must be minimised. The object of the invention is to provide a fibre optic cable having a high fibre count and a compact construction.